CVE-2026-25771 Wazuh Vulnerable to Denial of Service via Synchronous I/O Blocking in Asynchronous Authentication Middleware
An unauthenticated attacker can cause a denial of service in Wazuh API by flooding requests with invalid Bearer tokens, blocking the event loop.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-25771?
CVE-2026-25771 is a medium-severity denial of service vulnerability in Wazuh Wazuh, published on 17 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Wazuh is a free and open source platform used for threat prevention, detection, and response. Starting in version 4.3.0 and prior to version 4.14.3, a Denial of Service (DoS) vulnerability exists in the Wazuh API authentication middleware (`middlewares.py`). The application uses an asynchronous event loop (Starlette/Asyncio) to call a synchronous function (`generate_keypair`) that performs blocking disk I/O on every request containing a Bearer token. An unauthenticated remote attacker can exploit this by flooding the API with requests containing invalid Bearer tokens. This forces the single-threaded event loop to pause for file read operations repeatedly, starving the application of CPU resources and potentially preventing it from accepting or processing legitimate connections. Version 4.14.3 fixes the issue.
Weakness: CWE-400
Which versions are affected by CVE-2026-25771?
It affects 1 product.
Products include Wazuh Wazuh.
How do I fix CVE-2026-25771?
No fix has been published for CVE-2026-25771 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-25771 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-25771 exists.
Other vulnerabilities in Wazuh Wazuh
- CVE-2025-24016 Wazuh Server Deserialization of Untrusted Data
- CVE-2024-32038 Wazuh Analysis Engine Event Decoder Heap-based Buffer Overflow Remote Code Execution Vulnerability
- CVE-2021-44079 Command injection in n/a
- CVE-2024-1243 Remote code execution and local privilege escalation in Wazuh Windows agent via NetNTLMv2 hash theft
- CVE-2026-61800 Wazuh cluster worker file sync allows arbitrary file write under /var/ossec (incomplete fix for CVE-2026-30893)
Sources
Also known as GHSA-33w3-p5hm-jw7g.